Due to the above mentioned insulating gap between the exhaust gas pipe section and the cooling housing, the cooling housing does not withdraw much heat from the exhaust gas which is desirable because it is thus possible to supply the exhaust gas at a higher energy potential to a super-charger. However, it is necessary that the exhaust gas pipe section is surrounded by a housing that keeps its temperature within the range of the temperature of the cooling liquid of the internal combustion engine in order to satisfy operation requirements for engines that are intended to run without monitoring.
U.S. Pat. No. 2,125,703 (J.G. Williams), issued on Aug. 2, 1938, discloses an exhaust gas duct in which the exhaust gas pipe section is directly centered at the outer diameter of both pipe ends in the housing of the duct. A radial pin is provided for fixing the exhaust gas pipe section in the axial direction. The radial pin passes through the housing, as well as through the wall of the exhaust gas pipe section. Additionally, the exhaust gas pipe section is supported locally at the edge of each of the entrance passages or openings for the exhaust gas into the pipe section. This type of construction results in fretting corrosion at the points of contact between the components of the duct, due to the substantial heat expansion differences that occur during operation between the housing and the pipe section. These heat expansion differences cannot be avoided, due to the large temperature differences between the pipe section that is directly in contact with the exhaust gas and the housing components that are liquid cooled.
Such fretting corrosions may become the cause for structural changes of the components that are in frictional contact with each other and such changes may in turn become danger points which impair the further operation of the internal combustion engine. This danger is particularly undesirable because the points where the fretting corrosion may occur are not easily accessible, and hence not easily detectable when inspections are made.